1.2- Dimethoxy-8-phenyl-naphthalene

Dimethoxy-2,7-dimethyl-4-phenyl-l-benzoxepine heated 24 hrs. at 120° with exclusion of air in a Pyrex-ampoule 2,4-dimethoxy-2,6-dimethyl-3-phenyl-naphthalen-l(2H)-one. Y 90%. H. and P. Hofmann, A. 1975, 1797. 

The relative ease of sulfonation of 235 in comparison with chalcone 231 is due to the greater reactivity of the naphthalene nucleus towards electrophilic substitution and the orientation of sulfonation occurs in the predicted 4-position of the naphthalene ring in view of the electron-donating character of the alkenic double bond. 2-, 3-, and 4-Methoxy, 3,4-dimethoxy- and 4-phenyl-chalcone, together with the 2-thienyl and cinnamylidene analogues reacted with chlorosulfonic acid (six equivalents or three equivalents in thionyl chloride) at room temperature to give the corresponding sulfonyl chlorides. The orientation of sulfonation was discussed in terms of stereoelectronic factors and was confirmed by NMR spectral analysis. 

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